Accuracy of cytologic diagnoses made from touch imprints of image‐guided needle biopsy specimens of nonpalpable breast abnormalities

We investigated the diagnostic utility and accuracy of touch imprints (TIs) prepared from core‐needle biopsy (CNB) specimens of nonpalpable breast abnormalities. We reviewed air‐dried, Diff‐Quik‐stained TIs prepared from 172 consecutive CNB specimens obtained with stereotactic or sonographic guidance. Using criteria established for fine‐needle aspirates, TIs were categorized as benign, atypical, suspicious, malignant, or unsatisfactory (i.e., showing fewer than six benign epithelial cell clusters or cell distortion). Cytologic diagnoses of TIs were then correlated with the histologic diagnoses of corresponding CNB specimens. CNB specimens were histologically diagnosed as carcinoma (102 cases), benign (59 cases), low‐grade phyllode tumor (six cases), and atypical ductal hyperplasia (five cases). TIs were cytologically diagnosed as malignant (63 cases), benign (35 cases), suspicious (19 cases), atypical (18 cases), and unsatisfactory (37 cases). Correlation of the cytologic and histologic diagnoses showed that five TIs diagnosed as benign were false‐negative results for histologically diagnosed carcinomas (four cases) and phyllodes tumor (one case). False‐negative results were attributed to poor representation of malignant cells. Two TIs diagnosed as suspicious were false results for two histologically diagnosed fibroadenomas. The false suspicious findings resulted from TIs with high cellularity, cytologic atypia, or no familiar (i.e., as seen on fine‐needle aspirates) smear pattern. Unsatisfactory TIs were noted in both benign (44%) and malignant (11%) CNB specimens. When lesions categorized as suspicious were grouped with the malignant cases and those classified as atypical were grouped with the negative cases, TI sensitivity and specificity were 83% and 95%, respectively. Fibroadenomas are difficult to identify on TIs and are likely to be misdiagnosed as suspicious. While high‐ and intermediate‐grade carcinomas are easily categorized using TIs, low‐grade carcinomas are best categorized as suspicious because of overlapping cytologic features with proliferative breast lesions. Increased experience with cytologic analysis of TIs improves the accuracy of cytologic diagnoses. Diagn. Cytopathol. 23:29–34, 2000. © 2000 Wiley‐Liss, Inc.